How to send TTL output from Arduino Uno to Raspberry Pi?

Question

I am trying to send TTL pulse at 1second interval to Raspberry pi? Can someone suggest me a good way to do it using GPIO or any other way possible.

Arduino Code:

void setup() {
 pinMode(12, OUTPUT);
}
void loop() {
 digitalWrite(12, HIGH); // turn the LED on (HIGH is the voltage level)
 delay(1000); // wait for a second
 digitalWrite(12, LOW); // turn the LED off by making the voltage LOW
 delay(1000); // wait for a second
}

Raspberry Pi Code:

import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BCM)
pinTTL = 4
GPIO.setup(pinTTL, GPIO.IN)
start_time = time.time()
t_end = start_time + 60
while time.time()<t_end:
 inputState = GPIO.input(pinTTL)
 if inputState == True:
 print 'HIGH', time.time() - start_time
 else:
 print 'LOW', time.time() - start_time
GPIO.cleanup()

Another thing is I have checked using multimeter, the voltage on Pi output pin does change at 1second interval.

• joan: What have you tried? Where is your Arduino code? Where is your Pi code? How have you dropped the Arduino 5V GPIO to a Pi safe 3V3?
• raj: I have dropped the 5v arduino output to 3.3v for making it safe for Pi. I just used a normal arduino code for setting the pin output high and low at 1second interval to see if this works and whether the raspberry pi input pin detects that but I coulnd't get it work
• joan: Edit your question and include the Arduino and Pi code you are using.
• raj: added the scripts
• joan: Presumably you haven't connected the correct Arduino pin to the correct Pi pin. Please add a photo. abyz.co.uk/rpi/pigpio/index.html#Type_3 shows the position of GPIO4 on pin 7.

Answer 1

The problem lied somewhere in connection only. Changing the pinTTL=6 solved the problem.